In recent years, MOS (Metal Oxide Semiconductor) solid-state imaging devices have been extensively developed as solid-state imaging devices suitable for application to digital video cameras, digital still cameras, and the like. Such a MOS solid-state imaging device is configured to amplify and extract a signal charge resulting from photoelectric conversion performed by a photoelectric conversion element for each pixel. The MOS solid-state imaging device has a feature that a drive circuit for a pixel array including pixels that are two-dimensionally arranged in rows and columns and a signal processing circuit can be integrated on the same chip as the pixel array.
As the signal output system of the MOS solid-state imaging device, a column-parallel output signal output system that selects a plurality of pixels of the pixel array on a row-by-row basis and simultaneously reads out the signals of the pixels of the selected row in the column direction (the direction along pixel columns) is mainly used. Various configurations have been proposed for the signal output circuit of this column-parallel output solid-state imaging device. As one example of the most advanced forms of such configurations, a MOS solid-state imaging device is known that is equipped with a column-parallel AD conversion device having a configuration in which an AD converter is disposed for each column and analog signals output from pixels are extracted as digital signals.
FIG. 21 is a block diagram showing a MOS solid-state imaging device 10 equipped with a column-parallel AD conversion device described in Patent Literature (PTL) 1.
As shown in FIG. 21, signals generated by a plurality of pixel cells 11 are simultaneously read out to a plurality of vertical signal lines 22-1, 22-2, . . . 22-m that are respectively disposed for the columns. Additionally, the solid-state imaging device 10 includes comparators 31, and the signals that have been read out to the vertical signal lines 22 are simultaneously AD-converted by column-parallel AD converters 23-1, 23-2, . . . 23-m disposed respectively corresponding to the vertical signal lines 22-1, 22-2, . . . 22-m. 